1. Field of the Invention
This invention relates to an information retrieval system which retrieves documents stored in a storage apparatus (document storage apparatus) based on inputted retrieval terms including a plurality of keywords, weights of the keywords and so forth.
2. Description of the Related Art
In conventional information retrieval systems which are normally realized by an information retrieval apparatus, an electronic filing apparatus and so forth, it is an ordinary technique to store retrieval histories to facilitate re-retrieval of documents which have been retrieved once in the past.
For example, in an electronic filing apparatus disclosed in Japanese Patent Laid-Open Application No. Heisei 5-46685, histories of operations and retrievals for documents are stored in advance, and when re-retrieval by a retrieving person is to be performed, those documents which have been retrieved in the past by the retrieving person are displayed in order.
However, such conventional information retrieval systems cannot be used for retrieval of a document which has not been retrieved by a retrieving person itself in the past. Therefore, for such retrieval, new retrieval terms are presented to effect retrieval of documents to be retrieved, and if it is determined necessary based on a result of the retrieval, then new retrieval terms must be presented. Consequently, much time and complicated operations are required for such retrieval.
The conventional information retrieval systems described above have the following problems.
The first problem resides in that a retrieval history of an outsider cannot be referred to. The reason is that, in the conventional information retrieval systems, only re-utilization of a retrieval history regarding retrievals performed in the past by the retrieving person itself is taken into consideration.
The second problem resides in that a retrieval term cannot be searched based on a similarity of retrieval terms. The reason is that, when "re-utilization of a retrieval history of retrievals performed in the past by the retrieving person itself" is to be performed as in the conventional information retrieval systems, since information of the time of retrieval, a result of the retrieval and so forth can be utilized as elements for searching for a retrieval term (such retrieval elements are well known to the retrieving person since the retrieval has been performed formerly by the retrieving person itself), the conventional information retrieval systems do not attach great importance to a similarity between retrieval terms.
The problems described above fundamentally originate from the fact that the conventional information retrieval systems "cannot utilize retrieval terms in a retrieval history of retrievals performed formerly by an outsider."